Skywriting, one of the oldest methods of creating aerial messages, is the process by which a single aircraft emits a continuous or nearly continuous biodegradable vapor trail while twisting and turning to “write” each letter in the sky. The aerial messages produced by skywriting, which are capable of being seen from the ground for many square miles, provide a dramatic way for companies to advertise their products or services. However, the popularity of wide-spread skywriting is limited by several factors, including the risks involved in making the aerobatic twists and turns inherent in skywriting, the high degree of aviator skill required to make such precise maneuvers, and the substantial costs in creating even short aerial messages. Additionally, the length of aerial messages created using skywriting techniques is limited because strong winds may blur or dissipate the beginning letters of a long message before the aviator can make all of the twists and turns necessary to complete the message, thereby lessening the otherwise dramatic effect of the aerial message.
To improve the feasibility and ease of creating aerial messages, aviators began using multiple aircraft flying in formation to create messages, with each aircraft emitting short “puffs” of vapor or smoke in a defined pattern to form the individual characters (e.g., letters, numbers, etc.) of the messages. The resulting messages, which are created within a single pass, look like the printouts from a low resolution dot-matrix printer, with individual characters being formed by a pattern of vapor puffs that resembles the pattern of ink dots produced on paper by a dot-matrix printer. Thus, rather than “writing” aerial messages using only a single aircraft, the messages are “printed” in the sky using five or more aircraft, with each aircraft contributing a portion of each character. In order to accomplish the coordination necessary between the multiple aircraft, a master or lead aircraft uses a transmitting device to transmit a plurality of discrete tones or radio signals to the remaining (i.e., receiving) aircraft. These receiving or slave aircraft emit vapor puffs in response to the radio signals received from the master aircraft.
Although an improvement over traditional skywriting techniques, several problems are commonly encountered by existing systems. For example, in order to rearrange two slave aircraft into different positions in a flight formation, existing systems require that the pilots of the two aircraft mutually agree via their radio system to switch positions and then physically adjust their respective receivers to receive the signal originally intended for the other aircraft. Additionally, because the receiving units in each slave aircraft are configured to receive discrete radio frequencies, the units are not easily interchangeable into other slave aircraft.